Telephone-exchange system



G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED NOV. 29, 1926.

1,408,125. Patented Feb. 28, 1922.

2271/5772? 3 gym-" 152mm? G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV- 29, 1920.

Patented Feb. 28, 1922.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 29, 1920- I0 SHEETS-SHEET 3- Patented Feb. 28, 1922.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 29, I920.

Patented Feb. 28, 1922.

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Patented Feb. 28, 1922.

e. E. MUELLER. TELEPHONE EXCHANGE SYSTEM! APPLICATION FILED NOV- 29, I920.

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TELEPHONE EXCHANGE SYSTEM.

APPLlCATION FILED NOV. 29. 1920. I

. Patented Feb. 2 8, 1922.

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G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 29.1920.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 29, 1920- Patented Feb. 28, 1922.

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G. E. MUELLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV- 29, I920.

7 Patented Feb. 28, 1922.

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GEORGE E. IVIUELLER,OF LAlGRANGE, ILLINOIS, ASSIGNOR TO KELLUGG'SWITCHBOARD AND SUPPLY COMPANY, OF.CHICAGO, ILLINOIS, "A CORPORATION OF ILLINOIS.

Specification of Letters Patent. Patented Feb; 28, 1922 Original application filed June 20, 1908, Serial No. 439,582. Divided and this application filedNovember 29,1920. Serial No. 426,973.

To all whom it may com-era Be it known that I, GnoRenEfMUnLLnn, a. citizen of the United States, residing in La Grange, in the county of Cook and State of Illinois, have invented new and useful Improvements in Telephone-Exchange "Systems, of which the following is a specification.

My invention has to do with automatic and semi-automatic systems, and 'l'have elected to illustrate the same as embodied in the system of the latter class. The invention is directed to a system wherein selective switches are employed to interconnect subscribers telephone lines for conversation so organized that impulse transmitters atthe subscribers stations are unnecessary. To do this I provide a number of operators positions at the exchange, each having included in its apparatus one or more impulsetrans: mitting devices to be actuated by operators. I am'aware that systems of this general character have heretofore been proposed and the present invention directed toward certain improvements in such systems.

An object of the present invention is to provide means for automatically connecting the circuits at the exchanges over which conncctions are to be completed, with idleoperators calling devices, and then automatically disconnecting the circuits from such devices to render them available for further use as soon as the impulses have been transmitted. The connection of the exchange circuits with the calling devices may be automatically (if fected ina variety of ways, and I have illustratedtwo general ways in which this may be accomplished, one way requiring the use of selecting switches to effect the connections, and the other accon'lplishing the result by means of relays.

Another object of the invention'isto provide, in combination with the beforeindicated system, an improved operators transmitting device. in the organized system of my invention, a plurality of impulse sets must be transmitted to complete each connec tion for instance, one set representing the thousands, another set the hundreds, and other sets the tens and units. Assuming a maximum of ten impulses per set, ten buttons will be provided, preferably numbered according to the number of impulses they are adapted to transmit. Different buttons may serve to transmitthe four sets of impulses required for a connection according to the digits of the number to be transmitted or in case each set of impulses shouldbe of the same 'd git'value, as for example 3333, the 3 button will be depressed by the operator fourtimes. The buttons employed may operatein the manner of the customary order wire buttons, being actuated by an operator and immediately restored when released. Thus, a simple impulse transmitting device is provided and onecapable of rapid operation. Other objects of the invention will be referred to in the detailed description, and the scope of the invention will be strictly pointed out in the claims.

This application is a divisional application of my application SFN. 439,582,filed June20, 1908.

Referring to the-drawings, I have illustrated in Fig. 1, consisting of the parts 1 to 4:, inclusive, circuits of a semi-automatic tele phone system arranged in accordance with my invention.

Fig. 2 illustrates a circuit adapted for employment when trunking between exchanges is employed.-

Fig. 3 illustrates a modified first selector circuit and its auxiliary mechanism.

Figs. 4 and 5 illustrate other modifications of'first selector circuits.

Fig. 6 illustrates a modified operators inipulse transmitter arrangement.

Figs. 7, S and 9 are elevations of a selective switch which maybe employed in connection with the circuits of my invention.

Fig. 10 shows detail of the-primary offnormal switch of saidselective switch.

Fig. 11 is a sectional view showing in detail the arrangement of a primary magnet, with its associated mechanism, of said-selective switch.

Referring first to Fig-(1, parts 1, .2 and, 4, are to be placed in the order indicated with part 1 at the left, part '3 being placed immediately above part 2' to constitute a. complete circuit diagram illustrating apreferred embodiment of the invention.

The sheets being arranged in the way indicated, it will be observed-that at C and D I have indicated two substation telephone circuits of Well-known character whereof C in the present description will be the calling substation andD the called substation.

The instrumentalities employed in completing a connection between the calling station C and the called station D will include a line selector E which starts its travel upon the initiation or a call at substation C and automatically picks out the calling line. Simultaneously with the starting of the switch E, another automatic switch F paired with theswitch E starts into operation and automatically selects an idle first selector H. Thereupon, the switch K associated with the first selector H has its circuit connections changed sothat a signal pertaining to an operators impulse transmitter will be displayed at the operators position, the circuits of one transmitter being shown in Fig. 1, part 3. It may be stated at this time that the switches K, one of which provided for each first selector H, have before their wiper contacts 128, 129, 130, 181, multiple contacts 132, 133, 13 1, 135, each set of multiple contacts being connected to a different impulse transmitter and the signal associated with it. When the first selector His idle, the wipers of its associated switch K will rest engaging the multiple contacts of an idle transmitting device. Should the multiple contacts of such transmitting device be made busy, the wipers of the switch 1Q will be automatically moved free from thecontacts of the then busy device and will seek out contacts of an idle device.

When the calling line has thus been extended to an impulse transmitting device, the call signal associated therewith will be displayed and the operator observing the signal, ascertains the want of'the calling subscriber, and actuates the buttons of the calling device to count out the called subscribers number; whereafter the impulse transmitter automatically transmits .the proper impulse to adjust directively operable switches to connect with the called-forline. In the present instance, a ten thousand line system is illustrated, in which case first selectors H are employed toselect the thousands second selectors L to select the hundreds, and the connectors M to select the tens and units. Each first selector H has before its wipers 119, 120,121 a plurality of groups of multiple contacts 166, 167, 168, each group forming terminals of second Selectors L assigned for connections to a different thousand. Further, each second selector L has before its wipers 180, 181, 182, a plurality of groups of multiple contact sets, 183, 184i, 185, the sets of each group forming terminals of connectors M assigned'for connection to a different hundred of the thousand which the second selector L serves. Further, each connector M has before its wipers 21%, 215, 216, a plurality of groups of multiple contact sets 22, 23, 2 1, the said contact sets forming multiple called terminals of subscribers lines. There are preferably ten groupsof contact sets, each group including ten sets, the groups being arranged before the wipers of the connectors M according to their tens values.

111 the system of my invention, the subscribers lines may all terminate in a single exchange or they may be divided so as to terminate among a number of different exchanges. Preferably, however, in any case all the operators positions are to be placed in a single locality, as this will materially decrease the expenses of operation as compared with a system in which it is necessary to provide operators quarters in a number of places.

Assuming now a system having eight thousand subscribers lines, divided among four different exchanges, there being thus two thousand lines in. each exchange, and assuming further that all operators transmitting devices are to be placed in one of these exchanges, apre'l erred arrangement is as follows: The subscribers lines of each exchange will have assigned to them, as calling lines, a suitable number of first selectors H together with a suitable number of pairs of switches E and F to. interconnect the said calling lines with the first selectors. The

first selectors H would have before their wipers 119, 120, 121, not only terminals of groups of second selectors for connections with the two'thousand lines terminating in that exchange, but would also have before said wipers groups of terminals of trunk lines extending to second selectors in each of the three other exchanges. In this way each first selector H may be operated to pick out local trunk lines for connection within the exchange, or to pickout long trunk lines extending to any desired one of the other exchanges.

As before indicated,'each first selector H of the exchange now under consideration has its associated individual switch K connected with the wipers 136, 137, 138, 139; these wires, assuming that the operators exchange H is not the one now under consideration, are long conductors extending from "the exchange now under consideration to the operators exchange. For each connectionto be completed, a trunk line consisting of wires 136, 137, 138, 139, will be used for a short space of time only, namely, long enough for the operator to ascertain the number of the called-for subscriber and for the calling device to automatically count out the digitsot the called number, whereupon, as before indicated, the calling device and the trunk line including the wires 136, 137, 138, 139, are instantly freed. Thus, while each trunk to the operators position as illustrated requires four conductors (although the invention is not limited to the particular arrangement shown), a very small number of such trunk circuits will suflice to handle a large iuimber of calls on account of the short use required for each call.

Referring now to the exchanges of two thousand lines each, the two thousand lines oi? the exchange, at which the line of calling subscriber Q terminates, are preferably di vided as calling and called lines into twenty groups of one hundred lines each. Each group of one hundred lines would, on the usual ten per cent basis, have ten connectors M. assigned making conneiions therewith. As calling lines, each one hundred line group would have ten line selectors l5 con'unon to the group and of course an equal number of paired automatic switches F. The first selectors H, of which there would be preferably two hundred, would be divided into two groups oi one hundred each and their multiple contacts 81, 82, 83, would appear before the wipers "[6, TI, 78, of one hundred switches F so that each one hundred of'first selectors H would be common to one thousand calling lines;

For each one hundred lines as calling lines, the master switch mechanism G is provided, which serves whenever one of the lines initiates a call to start the switch of an idle pair Eli whereoiithe switch ill will select the calling line and the switch F will select the idle first selector H.

Assuming that the callin subscriber "C desires his line to be connected for conversation with that of the called subscriber D whose line will for the present beassunied to terminate in the same exchange as that of C" and whose number is 1238, the calling subscriber C removes his receiver from its hook whereupon hooklever 1O rises "-1 the customary mannerand closes a conductive bridge at the substation. Circuit may thereupon be traced from ground through the line relay 13, normal contact 18, line limb i2, raised hook-lever 10, returning over line limb 11, contact 21, to battery B. The multiple contact sets 27, 28, oithe subscribers lines at the line selectors E are normally unselectable owing to the private contacts 26 being grounded through normal contact 19 and M. ()n the operation of relay l3, armature l is attracted, removing ground from the private contacts 26 of the calling line C at the line selectors, thus. rendering them selectable, and maid armature 11-, by engaging its front contact, ogerates subgroup relay 25 over thecommon conductor 34, whereby the relay attracts its armature and ungrounds the multiple group contacts 29 of the sub-group at the line selectors. Ti lie relay 13, by armature- 15', places ground upon the multiple private called contacts 22 of the calling line, rendering them busy against incoming calls. Aru'iature 16 of relay l3 disconnects the relay from the calling line and locks the same in series with the master-switch relay 36 over toe common conductor which has one hundred branches, one to each line relay oi the one hundred line which the master-switch serves.

T he line selectors E are preferably doubleacting switches or the type illustrated in Figs. 7 to 11, having before their wipers 30, S1, 82, one hundred, sets of multiple calling contacts 26, 2?, 28, aranged in ten groups of ten contact sets each. it is, therefore, necessary, when the line select-or E is started in its travel, to first select the subgroup in which the calling line is located and thereafter select the calling line out of the previously selected group. For the purpose of controlling the line selectors travel in selecting the group, each subgroup of ten lines has a group relay 25 controlling the multiple group contacts 29 for that subgroup. lo engage with the contacts :29, a group selecting wiper 33 is provided which controls the travel of the started line selector E in selecting the group, said. wiper 33 moving with the wipers 30, 31, 32, on their primary travel. When the wiper 33 enan ungrounded contact 29, the primary travel of. the line selector E ceases and wipers 30, 31, 82, have trien selected the subgroup in which the calling line has its contacts. Thereafter the said wipers 30, 31, 32, begin traveling in an intersecting plane, while the wiper 33 remains motionless, to pick out the calling line.

Before proceeding with a further description of the circuits, 1 will briefly refer to the mechanical drawings of Figs. 7 to 11 which illustrate more specially a line selector, although the same mechanism is adapted for the switches ll and also for the first and second selectors and the connectors used in the system. V

In the side elevation of Fig. 7 one group oi ten contact sets is illustrated, each set consisting of three contacts 26, 27, 28. In

8, showing the front view of a conbanlz. each set is represented by a single short line, this view, therefore, disclosing ten groups of ten contact sets each. As indicated, the contact sets are arranged as if projecting through the inner surface of a section of a sphere. The wipers '30, 31,. 32, are first adjusted in arotary direc tion from leftto ri series of steps, each step bringing them beneath a different group of coi'itact When proper group has thus been selected the ends of the wipers 20, B1, 32, are rotated step-by-step upward over the contact sets of the selected group. For rotating the wipers to select the group, a primer lower reinity the group wiper 33 is mounted, the group contacts 29 being inserted in the base of the switch bank, one contact 29 being provided for each vertically "ending group of contact sets. The

Y shaft PS is provided at whose I wipers $30, 31, 82,, are pivoted in the primary shaft PS andhave a rearwardly extending part which engages a broad piece mounted upon the secondary shaft SS. The primary motion of the wipers to select the group is accomplished by rotating the primary shaft PS, while the secondary travel of the wipers is accomplished by moving the secondary shaft SS down, whereby the switch wipers are rotated in their pivoted bearing in the shaft PS.

For driving the primary shaft PS, a primary n'iagnet PM and an actuating pawl 700 (see section Fig. 11,) is provided, the said pawl being arranged to engage successive teeth of the ratchet shown attached to primary shaft PS. .X retaining pawl 701 engages teeth of said ratchet and holds the same against back movement under the influence of the spiral spring 706. Successive actuations of magnet PM prevail to move the ratchet, shaft and wipers step-bystep from left to right. The piece upon the secondary shaft SS engaging the rearwardly extendin portion of wipers 80, 31, 32, is sufficiently broad so that it remains in engagementwith said part of the wipers in whatever position they may be adjusted latterly.

After the primary adjustment of shaft PS, the secondary magnet SM is actuated a. number of times, each actuation produc ing a stroke of pawl 702 which engages successive teeth in its associated ratchet on shaft SS, said shaft being thus moved step by step downwardly, the retaining pawl 7023 holding the same against back movement, which would otherwise occur under the influence of spring 707 acting upon the pivoted arm 708 which loosely engages a screw threaded to shaft SS, as indicated in Fig. 9. Each step of shaft SS will obviously move the contact ends of wipers 30, 31, 82, a step upwardly and with each step they engage a different contact set. of the previously selected group.

After the wipers have been adjusted and are to be restored to normal, the release magnet RM is actuated. Its attracted armature 704 then. engages an end of the pivoted retaining pawl 701 of the primary ratchet. This withdraws the pawl from the primary ratchet. Simultaneously therewith the pawl 703 is, by an arm 701 upon the pawl 701, withdrawn from engagement with the retaining ratchet of shaft SS. Spring 707 then avails to raise the shaft upward whereby the wipers of the switch are re stored as to their secondary travel. Until this occurs, the tension of spring 706 upon primary shaft PS is unavailing, because of the fact that tooth 705 of the piece 709 is engaging one of the teeth of the ratchet wheel of primary shaft PS. It will be noted that the extension 709 of shaft SS when at normal, as shown in Fig. 9, engages the lower extremity of the piece 709, holding the piece and tooth 705 in a raised position. On the first downward step of shaft SS, the piece 709 is freed and is moved downward by springs 54, 55, so thattooth 705 engages whatever tooth of the primary ratchet it is then opposite. When the secondary shaft in the restoring process reaches normal, it again raises the piece 709, tooth 705 disengages the primary ratchet and the tension of spring 706 is then effected to move shaft PS and the switch wipers back to normal. In addition to parts heretofore mentioned, each selective switch includes a primary ofi'- normal switch and secondary off-normal switch. As indicated in Fig. 10, the primary off-normal switch (which is indicated throughout the drawings by the letters PON), may include the springs 47 and 48, the former having an angular bent portion for engagment by the stud 710 mounted upon an arm 711 fastened to shaft PS. Obviously, on the first primary step, arm 711 will be rotated a step, stud 710 will free spring 47, whereupon the two primary off-normal springs, by their tension, will assume their alternate positions. The secondary off-normal switch, best shown in Fig. 9, may include the actuating springs 54 and 55 provided with a stud 709 normally engaged by the piece 709, whereby the springs 54, 55, are held in a definite normal position. On the first downward step of shaft SS, as before indicated, the piece 709 frees the secondary off-normal springs 54, 55, and they then move, by their tension, to engage their alternate contacts. V

i The mechanical structure shown in Figs. 7 to 11, inclusive, may be used without change for those portions of Fig. 1 indicated by E and F. For the first and second selectors and connectors, a similar switch structure may be employed, it being understood that the primary off-normal and secondary off-normal switch combinations indicated in the circuit drawings will be provided for the respective switches. Of course, when the mechanical structure is employed for a directively operable switch, the group wiper 38 and the group contacts 29 are not required.

Returning now to the description of the circuits shown'in Fig. 1, part 1, as soon as relay 13 operated, as before described, looking itself in series with the master-switch relay 36, the energization of the latter closed the contacts 37, 38. The wipers 41, 42, 43, normally rest engaging contacts 44, 45, 46, of an idle switchpair EF, as hereafter explained, and circuit may now be traced from ground at the armature of relay 39 through contact 38, contact 42, 45, normal contact 47 and grimary relay PR of switch E to battery energizing relay PR whose at tracted armature 41.9 connects the relays Winding with. the group, wiper 33. Armature 50 ot' relay PR close; a generator circuit for primary magnet PM and primary steps of the line selector E are now produced bysaid magnet, mo *ing the wipers on their primary travel until wiper 33 engages an ungrounded sub-group contact 29., because the relay PR will continue energized by current over locking armature if? through wiper 33 and to ground through normal, i. e, ground ed contacts 29 until. the sub-group contact of the group in which the calling line is included is reached at this time the attracted armature of the group relay 25 allows relay PR to be ale-energized and its armature retracted armature 50 then opening the circuit of magnet PM and prevent ing further primary steps of the switch. On the first primary step of switch lih the primary off-normal PON contacts 471 l8, were shifted the shitting of contact 4:7 opening the initial energizing circuit of relay PR which thereafter remains dependent upon wiper 33 for its continued energization. Circuit may now be traced from ground through normal switch contact 50 of relay PH, through closed contact 4C8, normal contact 54, secondary relay SE to battery. energizing said relay which, by armature 57, connects its winding with the circuit extending to the private wiper 30. Ari-mature 58, engaging its alternate contact, completes a generator circuit for secondary magnet SM traced through normal contact 52, so that magnet receives actuating impulses, stepping the wipers 30 81 32, up over the contact sets 26 27, 28, ot' the selected. subgroup seeking a contact set whose private contact 26 is ungroundecl. Relay Sltwvill continue encrpgizei'l until wiper SO-enga gee, an ungrounded contact 26 because 01''? the suc cessive locking circuits established by wiper 30 in engaging successive contacts 26 of lines not calling", said circuits being traceable through normal contacts 19 and i i. As soon however as wiper 30 engages the contact 26 ot' the calling line Cgtlie ungrounded condition of such contact causes the de-energization of relay SR and further actuations of secondary magnet SM will be prevented. The secondary oft-normal contacts and 55 were shifted on the first secondary step. of the-switch wipers so that thereafter relay SR depended upon the circuitthrough wiper 30 for its continued energization. The call ing line has thus been selected by the line selector E; i

The trunk selector was started simultaneously with line selector E by current from ground through the armature of relay 39 at attracted armature 37, contact 4C144L, primary off-normal contact 61 of switch F and its primary relay PR, which then attrncteil its armature 64 to close a circuit through primary magnet PM, which receives actuations to cause primary travel of the switch F. Armature 63 of the relay PR connects the relays winding with the group wiper 79, and relay PR will continue energized and magnet PM continues to receive actuations until the wiper 7 9 engages an ungrounded group contact 8% pertaining to a group oi first selectors H having one or more unemployed ones among it. The group con tacts S l of groups of first selectors H in which there is no idle switch are grounded as hereafter explained. Thus. as soon as the wiper 79 engages an ungrounded contact 84c, relay PE is de-energized, its armature retracted and further actuations of primary magnet- PM prevented. The primary offnormal contacts 61 and 62 of switch F were shifted on the first primary step, contact 61 opening the initial energizing circuit of relay PR which thereafter depended for its continued energization solely upon the wiper '79. ()n the de-energization of relay PR, circuit is traced from ground through nor mal contact 6t, the shifted contact 62, normal contact Y80, and secondary relay SR to battery. Said relay SR energizes and by armature 72, closes a generator circuit for the secondary magnet SM traceable through normal contact 66. Armature 70 of relay Elli connects the relays winding with the private wiper 7 6 and the relay SR will continue energized during the secondary travel of switch F until wiper '76 engages an ungro-unsfled,contact 81, which will be one pertaining to an idle first selector H; contact 81. of. busy first selectors being characterized by ground connect ons as hereafter explained. When wiper 76 engages the ungrounded contact 81. relay SR willbe deencrp ized its armaturcs retracted and further actuations of secondary magnet SM prevented, whereby wiper. i6 77, 78, rest engagingmultiple contacts Si, 82, 83, of the idle first selector The secondary offnormal contacts and S0 or switch F were shifted on the first secondary step, the shiftin of contact 80 opening the initial energiz ng circuit of relay SRand rendering; it dependent for current upon the wiper 76.

Immediately following the selection of contacts 81., 82, 83, or". first selector H, the relays PR and SR will be energized whether or not the line selector E has completed its selection. It said line selector E has not completed its selection relay SR will be energized and circuit will then be traceable from the positive pole of battery a relay PR normal contact 89, contact 82 77, normal contact 69, wire 25, alternate contact 56, normal contact 53, alternate contact 59, normal contact 74, contact 78-83, normal contact 90 relay SR to battery B Vi hen under the circumstances just described, switch E completes its selection, the

de-energization of relay SR will close a substitute circuit for relay PR extending through normal contact 56, contact 31-27, normal contact 19, cut-ofi relay 17 to battery, which relay by attracting its armature 18, continues the circuit of relay PR over the calling line, a return circuit being traceable over limb 11, contact 28- 32, normal contact at 59, and through relay SR to the negative side of battery B These circuit changes occur without allowing thede-energization of relays PR and SR on the actuation of relay 17, its armature 19 loclrs said relay via contact 28-30, armature of magnet RM and normal contact 57 'to ground. The armature 20 of relay 17 opens the locking circuit including relays 13and 3'6 and they are immediately de-energized, the de-energizations of relay 13 de-energizing the group relay 25 whereby the ground is restored to the group private contacts29. It will be noted that as soon as switch E completed its selection, retracted armature 57 places ground via wiper 30 upon the multiple contact 26 so that the contacts 26, 27, 28, of the calling line were rendered unselectable with respect to other line selectors. I1 the line selector E had completed its selection before the trunk selector F, circuit changes similar to those just described would have occurred except that the primary relay PR would have received its first energizing current in series with the cutoff relay 17 of the calling line.

As soon as both switches E and F complete their'selection, the wipers 41, 42, 43 of master-switch (l move away from contacts 44, 45, 46, 01 the switch pair in search of other similar contacts pertaining to an idle switch pair El it being understood that each switch pair El serving a given hundred lines has its contact set 44, 45, 46, at the mastor-switch of that one hundred lines. The master-switch G: may be a simple rotary switch comprising the customary rotary ratchet, shaft and wipers and a magnet 49 having the customary ratchet driving pawl, the contacts 44, 45, 46, being arranged to germ a complete circle. lt will be observed mat as soon as the two switches E and F have completed their selection, circuit is traceable from ground at normal contact 52 of relay Bil, through normal contact 58, alternate contacts 55 60, normal contact 7 through contact 4643, relay 39 of master switch G to battery. Relay thereupon attracts its armature, removing ground from the starting wipers 41, 42, and closes circuit for the steppin magnet 40 which thereupon steps the wipers 42, 43, rot-arily over the contacts 44, 45, 46, until they erigagetonta'cts of a normal, i. e, idle switch pair EF, the contacts 46 of busy switch. pairs being grounded over circuits similar to that before described.

157 to battery.

The multiplecontacts 81, 82, 83 of the first selectors H, are preferably arrangd in ten groups of ten contact sets each, before the wipers of switches F. Each such group of contact sets is provided with a multiple group contact 84 atthe switches F. The contacts 84 01"" a group are connected to a conductor 84 which may be extended through primary off-normal (PON) contacts 99,99399", etc, to a ground connection. The contact 99, shown in Fig. 1, pertains to the first first selector H of the group, contact 99 is for the second first selector of the group, and 99 is for the third one and addi tional contacts 99, one for each of the other seven first selectors (assuming a group of ten) will be provided with similar connections. Thus, if all the first selectors H of a sub-group have been moved off normal, the ten primary off-normal contacts 99 of these switches will be closed and the multiple group contacts 84 of the sub-group will be accordingly grounded. To take care of the condition arising when a first selector H has been selected, but has'not been moved off normal, the relay SE of each first selector is provided with an armature 95 having connections, adapted, when the relay is energized, to close a branch circuit about the oil! normal contact 99 so that as soon as selector H isselected, the circuit of the group contact 84 is extended to the primary off-normal contact 99 of the next first selector in the series.

As soon asrelays PR and SR are operated, as before described, circuit is closed as follows: From battery B through primary oil-normal *(PON) contact 100, normal contact 103, attracted armature 94 ofrelay PR through normal contact at 124, relay 122 to ground, whereon relay 122 attracts its armature and closes a circuit extending from ground through said relay, armature 124, contact 131-135, over wire 139, switch 140, contact 141, and lamp 143 to battery, light i11 said lamp atthe opera-tors position to in icate the call. The wipers 128, 129, 130, 131, in the form of invention now being de scribed, normally rest engaging the contacts 132, 133,134,135,pertaining to an idle opera tors calling device and its associated signaling apparatus. As soon as relay 122 operated, as before described, a circuit was closed as follows: From ground through relay 85, attracted armature 1.28, contact 130 134, over wire 138, normal contact 156 and resistance Ground through 85 now being placed upon the multiple contacts 134 of the operators device, said contacts 134 will be rendered busy with respect to any other switch K engaging them. Thus, if at this time, more than one switch K had their wipers engaging the contacts 132, 133, 134, 135, of the calling device of Fig. 1, part 3, all such switches K except that one connected with the first selector H would have their operating relays OR energized which relays would close the circuits of their respective magents OM and the switches would initiate rotary travel after the manner of the master-switch G to seek out contacts or an idle operators device. As soon as such contacts were encountered, the relays OR would be de-energized owing to the absence of ground upon the contacts 13% of such calling device and the switches would be arrested.

The operator observing the display of the call-lamp 14.3, associated with the calling device shown in Fig. 1, part 3, actuates levers 155, 155 156, of a listening key, levers 155, 155 then bridging her talking set across the wires 136, 137, which extend via wipers 128, 129, and contacts 126 and 127 to the first selector H and there terminate in armatures 86 and 87 of relay 85. The shifting of lever 156 de-energizes relay 85 by disconnecting battery from conductor 1-38 and retracted armatures 86 and 8'? connect the operators talking set with contacts 82 and 83 ouer which a talking circuit may be traced to the calling substation C over the heavily marked conductors, such heavily marked. conductors being employed throughout the drawings to indicate the course of the talking circuit established between subscribers. The operator now ascertains from the calling subscriber the number of the wanted called subscriber assumed to be 1233, whereafter the operatorrestores her listening key levers, thus permitting .relay'85 to hex-again. operated and its armatures attracted. The operator now presses down and releases once the buttion actuatingthe spring set marked 1 in Fig. 1, part 3; then; presses and releases the button. actuating the spring set marked 2" and then presses and releases twice the but ton actuating thespring set marked 3. In the diagram of Fig. 1, part 3, those parts of the mechanism pertaining to the thousands are indicated by reference characters employing the letter M; those parts relating to the hundreds are identified by the reference character letter Cgthe tens by 1) and the units by U. For each thousands digit to be transmitted, a relay is provided, the relay M being the relay controlling the transmission of the thousands digit 1, the relay M controlling the'transmission of the thousands digit 2, and the relay M control ling the transmission of the thousand digit 3. For each number 4:, 5, 6, 7, 8 and 9, it

such thousands digits wererequired, an additional; relay would be provided having cir- ClHE connections corresponding to those of the relays M, M M ,as shown inFig. 1,.

part Thus, the. thousands digit relays will constitute a group. Similarly, for the hundreds, C isthe relay for'the hundreds digit 1, C for the hundreds digit 2, and C for the hundreds digit 3 and other relays will be provided for the other hundreds digits to be transmitted, the hundreds relays forming the second group. Similarly, relays D, D D are the relays for the tens digits 1, 2 and 3, and relays ll, U U, for the units digits 1, 2 and 3. The alternate contacts or spring 1 2 3", etc, of the operators buttons are connected to wipers 160*, 160", 160", etc., of an auxiliary switch 2*. All of the wipers 160, of which there will be as many as there are digits to be transmitted, normally rest engaging contacts M connected to the thousands relays of their respective digit values. lVhen as in the present instance, the thousands digit is 1 and the button actuating the springs 1 1", is operated, the relay M controlling the transmission of the thousands digit 1 will be energized and thereafter the wipe-rs 160 will all simultaneously move to engage their second contacts, those connected with their respective hundreds relays, so that the spring sets 1, 2, 3, 4:, etc., will then be all connected to their respective hundreds relays. .Vhen the button actuating the spring 2 is now operated, the relay C controlling the transmission .01": the hundreds digit 2, will be energized and the wip rs 160 will all be moved to the contacts D connected with the tens relays D, D D etc; then when the operator actuates the button controlling the springs 3 which will energize the tens relay D controlling the transmission of tens digit 3, the wipers 160 will all be moved to the contacts U connected with the units relays U, U ,U thereafter when the operator againdepresses the button con trolling the springs 3, the units relay U controlling the transmission of units digits 3 will be energized and the wipers 160 move an additional step. The apparatus being now, by the operation of"? the required relays, in the thousands, hundreds, tens and units groups set for the transmission of number 1233, the operator will actuate the button of the startingsprings S and the switch 3 will initiate its travel to transmit the number thus set up, the switch 2 being simultaneously restored to normal.

A general View of the operators transmitting mechanism of Fig. 1, part 3, having been given, its operation may now be re ferred to in detail. hen the perator actuates the button associated with spring set 1, springs 1 and l momentarilyengage their respective contacts. Current will then fiow from ground through contact 1 through contactlGW-H, through relay 1/ to--battery, said relay M thenattractingits armatureand locking itself via said armature in, contact H) and contact 142 to ground. Armature m also connects the ground at'142 with relay M, which operates to attract armature m to lock itself to ground at 1-12 and armature m similarly operates relay M whose armature m locks the relay to ground at .142. Armatures m, m of, have now removed ground at 142 from the first three contacts M" before the wiper 150 so that the fourth contact only remains grounded and but one impulse will be transmitted over wire 136 when wiper 150 passes over the contact H in the manner presently to bedescribed. The closing of contact 1 for a moment energizes and de-energizes the operating magnet (i of switch 2 and the armature controlled pawl 153 of said switch, on the de-energization of magnet 3 steps its associated ratchet one step. Said ratchet is fastened to the shaft 159 to which also the wipers 160 are fastened so that the said through spring 2 over 165", contact 160"C,

relay C to battery. Relay C? attracts armature 0 thereby locking itself from ground at contact 142' of switch 3 Armature 0 also connects said ground with the winding of relay G which looks. It will now be observed: that the first two contacts C have been, by the operation of armatures' 0?, 0 ungrounded. The contact C connected with armature 0, however, remains grounded, and since the last contact- C is permanently grounded, the wiper 1501when it passes over thehundreds contacts C, wil; transmit two current impulses from ground over the wire 136. The momentary closing of contact 2 energizes and tie-energizes magnet 6 whose attracted and retractedarmature steps the shaft 159 a step so that wipers 160 160 and 160 are advanced a step toengage their tens contacts D, respectively.

The operator now actuates the button for the spring set?) twice. On its first actuation, current flows from ground through spring 3", over 165, contact 160.--D, relay D to battery, and relay D by armature (Z then locking itself to ground at contact 142. The armature 65 removes ground from onecontact l) only in the-tens group, the remaining-three contacts I) remaining grounded so that when wiper 150 passes over said tens contact, it will transmit three impulses. from ground over wire 136. The first actuation of the button controlling the spring set-3 will, in an obvious manner, produce a third-step of wipers 160 ,160 160, so that they will engage their fourth contacts U.

The next actuation of the button controlling the spring set 3 will close circuit from ground through spring 3", through contact 160-U, and through relay U whose arma' ture a locks the relay and removes ground from the first one of the contacts U, the remaining contacts U remaining grounded so that when wiper 150 passes over said contacts it transmits three impulses from ground over the wire 136.

It will. now be seen that when the wiper 150 is caused to make one complete revolu tion in the direction indicated by the arrow, it will pass over the various contacts M, G D U transmitting to the wire .186 sets of impulses corresponding to the number of the called subscriber The wiper 149 being mountedon the same shaft 145, moves coincidently with the wiper 150 and as the said wiper 150 passes beyond the last contacts M C D, U, respectively, the wiper 149 will engage respectively the grounded contacts 151, 152, 153, 154, so that each set of impulses over wire 136 will be followed by a single impulse over the wire 137. p r

The operator now actuates the button controlling the starting spring set S. The momentary engagement of spring S with its contact, energizes and de-energizes release magnet r of the switchQ and the attracted armature 164 is effective to withdraw the pawl 163 from the ratchet of shaft 159-and its associated spring now restores the shaft 159 and the wipers160 to normal. 'The engagement of spring S with its contact closes circuit from ground over 165 through magnet O of'switch 3 and an impulse from the assooiated generator actuates magnet O to advance the ratchet 148, fastened to shaft 145, step; The spring 146 has a bent extremity normally engaging the notch in the disk shown fastened to shaft145. On the first step of shaft 145, spring 146 rides upon the periphery of the disk and engages its con-' tact, whereby the generator circuit of magnet O is continued when the momentary closing of contact S ceases. It will now be apparent that until the armature actuated pawl of magnet O has been operated a sufficient number of times to cause a complete revolution of ratchet 148 and shaft 145, contact 146 will remain close'chthe magnet 0' will receive successive impulses from the associated generator. As soon as one complete revolution is made, however, spring 146 again engages the notch of its associated disk and travel of the switch 3 ceases. The wipers149, 150 being fastened to shaft 145 will, of course, be rotated along with'the ratchet 148 and willhave completed one revolution when the switch 3 stops, impulses being transmitted over wires 136, 137 as before indicated. I y

Just before the switch 3 completes its revolution, an insulating pin 147 fastened in the disk mentioned, will pass over the top of the bent portion of spring 142, opening contact 142, and also contact 141-1. The opening of contact 1&2 unlocks all the relays M C, D and U, that were energized and thus restores this portion of the calling device to normal. The opening of contact 141 terminates the flow of current previously passing from battery through lamp 143, over wire 139, contact 135131, the attracted armature 12 1 and relay 122 to ground, whereby the relay 122' is de-energized and its armatures retracte'd, and the lamp 143 extinguished. The relay 122 is not again energized because the first step of first selector H will have opened the primary cit-normal contact 100. On the retraction of armature 123 of relay 122, ground is removed from the multiple contacts 134 so that any other switch K, which in its travel engages the contacts 132, 133, 134;, 135, may come to rest engaging such contacts. The apparatus of the operators calling device, illustrated in Fig. 1, part 3, has now been fully restored to normal and its associated trunk wires 136, 137, 138, 139, are now available for further use in putting through other connections. I

At a" in Fig. 1, part 3, Ihave indicated a spring set comprising springs rm and rt). This spring set, when actuated, will restore the switch 2 and any relays M, C, D, U, that may then be operated to normal, and is provided for the purpose of resetting the apparatus in case the operator may make a mistake in counting out the called number.

I have indicated at 165 165 165, 165 and 165 switch levers which may all be mounted upon a common shaft 165. By turning the shaft 165, a single operators set of buttons 1, 2, 3, etc., may be interchangeably associated with dilferent calling device switches in an obvious manner. Preferably, however, each calling device is provided with a separate set of actuating buttons.

It will be observed that the spring 49 is not provided with any associated contact and thus when the spring set 4 is actuated, no digit relay will be energized. Ttwill be seen that for transmitting the largest digit of any set, all the contacts before the wiper 150 for that impulse group are to be left in their normal grounded conditions. In the present case, the impulse transmitter is arranged to transmit a maximum of four impulses. When the device is arranged to transmit sets of impulses from one to ten inclusive, there will, of course. be relays for each of the digits from one to nine, inclusive, the but-ton 10 having connections then arranged to correspond with those of but ton 1 indicated in Fig. 1, part 3.

The method in which the first selector "1, the second selector L and the connector M operate in response to the impulses transmitted by the mechanism in Fig. 1, part 3, will. now be described.

The first set of impulses transmitted,

when wiper 1550 moved over contacts M con sisted of one I impulse, this passing over wire 136, contact 132128, contact 126, alternate contact 86, relay PR to battery, actuating said relay whose attracted armature first closed a maintainin circuit for sec ondary relay SR extending through contact 90, attracted armature 88 and alternate contact S9, whereafter normal contact 89 is opened and relay PR momentarily de-energized. (in the de-energization of said relay, its armatures retract and an impulse of current is transmitted from ground through attracted armature 97, normal contact 92,

pulse transmitted by wiper 1 19, Fig. 1, part' 3, over wire 137, passes through contact 133 129, contact 127, alternate contact 87, relay SR to battery, this impulse following immediately after the de-energization of relay PR and the re-attraction of its arma ture. The armature of relay SR is attracted, first establishing a maintainingcircuit for relay PR extending through normal Contact 89, attracted armature 88 and alternate contact 90, and then opens the circuit of relay SR tie-energizing the same. A current impulse then flows from ground through attracted armature 93, normal contact 93, contact 108, primary off-normal contact 110, shifted on the primary step, through busy relay BB to battery, actuatlng said relay whose armature 116 connects its winding via" contact 113 with the private WlPQT'llQ. Armature 117 now closes gencrater circuit for secondary magnet which produces secondary steps of thefirst selector H- which will 119 strikes an ungrounded, i. e., idle con tact 166. As soon as this occurs, relay BB tie-energizes and its armature retracts, armature 117 preventing further actuations of magnet 3M wipers 119, 120,121, resting i ing the multiple contacts 166, 167, 168, terminals of the selected idle second selector 1 L of the first thousand. It will be noted that while the wipers 120, 121, are passing over busy terminals 16?, 168, they are on open circuit at contacts 115', 113. Armature 116 has placed ground upon contacts 166, rendering them busy."

\Vhen wiper 150 passes over contacts C. two impulses will be transmitted overwvire 136. energizing and tie-energizing relay PR twire, which relay produces two de-energizacontinue until wiper multiple energized.

tact 115, 120-167, contact 170, magnet Plv 3 tot battery B Magnet PM then produces two primary steps of second selector L, moving wipers 180, 181, 182, adjacent to a group of multiple terminals 183, 184, 185, connected to connectors M assigned for connection to the second hundred of the first thousand. On the first primary step of switch L, the contacts 179 and 169 are shifted. After the transmission of the two impulses over wire 136'and the resulting two steps of switch L, a single impulse over Wire 1337 energizes and tile-energizes relay SR which de-energizes relay SR while relay PR remains operated. An impulse of current then flows from ground through contact 93, normal contact 98, contacts 118, 121-168, contact 179, busy relay BB to battery, actuating said relay which, by armature 176, connects its winding with the private wiper 180,,andby armature 177, closes a generator circuit for secondary magnet 8M which now causes steps of wipers 180, 181, 182, over successive contact sets 183, 184, 185, until an idle, e.', ungrounded set is encountered. As soon as this occurs, relay BB will be on open circuit and on its cle-energizationits armatures are retracted, armature 177 opening the generator circuit of magnet SM and by en 'aging its normal contact, said armature 1 7 places ground upon the mul tiple contacts 183 of the idle connector M to render them busy. The wipers 180, 181, 182, now rest engaging the multiple contacts 183, .184, 185, of the selector connector M. On the first secondary step of the switch L, the secondary oft-normal (SON) contacts 170, 171, were. shifted to their alternate positions.

When wiper 150 sweeps over contacts D, three impulses transmitted over wire 136 are effective to produce three de-energizations of relay PR in a manner obvious from the preceding description and three impulses are transmitted from ground atarmature 97 through contacts 92, 120-167, 181-184, normal contact 217, primary magnet PM to battery, whereby three primary steps of connector M are produced to move wipers 214, 215, 216, to positions adjacent to a group of ten contact setsincluding those of lines 1231 to 1239, inclusive, followed by contact of line 1230. On the first primary step of connectorM, the primary off-normal (PON) contacts 186, 187, are all shifted to their alternate positions. After this adjustment an impulse flowing over wire 137 deenergizes relay SR an impulse of current flowing from ground at attracted armature 93 through contacts 98, 121-168, 183-185,

normal contact 218, shifted contact 188,

magnet S M, to battery B Magnet SM engage the first set of contacts of the selected group, the connector being so arranged that the wipers after their primary adjustment are two steps distant from the selected contact group. This first step,however, causes secondary off-normal contact 217 to engage its alternate contact, while contact 218 disengages its normal contact, but is not moved sufliciently to engage its alternate contact.

As wiper 150 continues its rotation passing over the contacts U, three de-energizations of relay PR produced in an obvious manner, transmits three impulses from ground at contact 97 over the above traced path through. contact 181-184, alternate contact 217, normal contact 192, secondary magnet SM to battery, whereby three additional secondary steps of connector M are produced, and wipers 214, 215, 216 are moved to engage the contact set 22, 23, 24 of the third line of the group, said contacts being terminals of line 1233 whose substation is illustrated at Immediately fol: lowing this, wiper 149 transmits an impulse over wire 137, the resulting de-energization of relay SR transmitting an impulse of current from ground at attracted armature 93 over the before traced path, through contact 182-185, alternate contact 218 (said contact having been closed on the second secondary step of connector M), through contact 196, the lower winding of test relay TR to battery. Said relay thereupon attracts its armatures whereof 206 connects the relays upper winding with the private wiper 214 to test the called-for line. Assuming first that the called line is idle, the condition illustrated, multiple contacts 22 are connected through normal contact 15 and the winding of cut-01f relay 17 with the active side of battery B As soon as theimpulse through th lower winding of relay TR ceases, the relay will now de-energize, both terminals of its upper winding being connected to the active side of battery B It will at this point be observed that the impulse through the lower winding of relay TR is momentary only because the attraction of its armature 207 instantly energizes relay 194 by current from battery through said relay, contact 207, normal contact 190, to ground. Relay 194, by armature 1'95, locked itself to ground at 190 and the attraction of armature 196 at once opens circuit through the lower winding of relay TR. On the de energiaation" of relay TR, circuit is traced from ground through relay 202, attracted armature 193, normal contact 206, contact 214-22, 15, cut-oil relay 17 of the called line to battery, current over this path energizing both relays 202 and 17. Theground through relay 202 now connected to multiple 

